Human conjunctival epithelial cells generate antimicrobial defensins in response to bacteria.
C. Rosenkranz, O. Flachmann
Purpose: The human eye continually confronts microorganisms at its mucosal surfaces. A current model suggests that epithelial cells contribute to defense at these sites, in part through the production of peptide antibiotics. Recent studies have shown that the human beta-defensin hBD-1 is synthesized constitutively in human conjunctival tissue, whereas the production of hBD-2 appears to be inducible by exogenous stimuli. These findings prompted us to investigate whether beta-defensins are present in the conjunctival epithelium. Moreover, we examined the capacity of these cells to produce defensin in response to exposure to bacteria.
Methods: Samples of normal limbal conjunctiva were excised from 20 individuals who underwent intraocular surgery. Informed consent was obtained from each patient. Each conjunctival sample was divided into halves. One half was challenged with E.coli or Staphylococcus aureus, control halves were left untreated. Each sample was incubated for 6hr or 24hr. Immunohistochemistry was performed on paraffin-embedded sections with anti-human defensin 1-3. Immunostaining was scored by light microscopy. Control experiments included the incubation of sections in the absence of primary antibodies.
Results: Conjunctival epithelium of control eyes exhibited weak or no immunostaining for human defensin 1-3. In contrast, we observed a marked increase in human defensin immunoreactivity after stimulation with bacteria.
Conclusions: The current study demonstrates the presence of defensin in the conjunctival epithelium and the capacity of conjunctival epithelial cells to produce defensin in response to various bacteria. In view of their broad spectrum of antimicrobial activity, defensins hold therapeutic potential in ocular infections.
Augenklinik, Johann Wolfgang Goethe Universität, Theodor- Stern-Kai 7, D-60590 Frankfurt